In a UMTS (Universal Mobile Telecommunications System) communications systems using W-CDMA (Wideband Code Division Multiple Access) and a so-called FDD (Frequency Division Duplex) mode, the so-called “Compressed Mode” procedure is specified to allow UEs (User Equipments), which e.g. have only one receiver part (e.g. for cost reasons), inter-frequency-measurements (i.e., e.g., on UMTS mobile radio cells, which are operated on another frequency band compared with the frequency band used for the current mobile radio cell in which the UEs are located) and inter-RAT (Radio Access Technology)-measurements (i.e., e.g., on mobile radio cells of another mobile radio communications system, e.g. GSM (Global System for Mobile Communication). A defined number of inter-frequency-measurements and/or inter-RAT-measurements may be defined in UMTS. Each of these measurements is configured for a UE by the mobile radio communications network using individual compressed-mode parameters.
In more detail, the “Compressed Mode” procedure generates transmission gaps in the uplink transmission direction (Uplink: e.g. signal transmission from a mobile radio terminal device to an associated respective base station) and/or in the downlink transmission direction (Downlink: e.g. signal transmission from the associated respective base station to the mobile radio terminal device), which should be used by the User Equipment UE for the respectively configured measurements. By way of example, in the case of the downlink transmission direction, the mobile radio base station (in the case of UMTS also referred to as NodeB) interrupts the data transmission to the mobile radio terminal device (in the case of UMTS also referred to as UE) during the period of the configured transmission gaps. Furthermore, in the case of the uplink transmission direction, the mobile radio terminal device (in the case of UMTS also referred to as UE) interrupts the data transmission to the mobile radio base station (in the case of UMTS also referred to as NodeB) during the period of the configured transmission gaps.
In those cases, in which transmission gaps are generated in the uplink transmission direction by the configured “Compressed Mode” parameters, this may result in performance losses with respect to the data throughput and the transmission delay, since e.g. data transmissions in the downlink transmission direction may not be acknowledged in time in accordance with the so-called HARQ (Hybrid Automatic Repeat Request) procedure using uplink transmissions.
This situation becomes more severe in future data services having high data rates and a HSDPA (High Speed Downlink Packet Access) transmission using a plurality of (e.g. two) mobile radio cells.